AU2008202722B2 - A Padlock - Google Patents

Abstract

Abstract A padlock where the shackle can be entirely removed from the padlock body when the padlock is open. The padlock has a selector screw which can be accessed through an aperture in the side of the padlock body. The selector screw engages with the camming member and a locking ball inside the padlock. The selector screw can be turned to a first position in which it prevents the locking ball from retracting far enough away from the shackle to allow the shackle to be removed. The selector screw can also be turned to a second position in which it allows the locking ball to retract away from the shackle far enough for the shackle to be removed. The selector screw cannot be turned from this first position to the second position except when the padlock is open.

Description

A PADLOCK FIELD OF THE INVENTION The present invention relates to padlocks, and in particular to padlocks where the 5 shackle can be removed from the padlock body when the padlock is open. BACKGROUND Padlocks are portable locks commonly used to lock doors, gates and the like. They can usually be removed from the door, gate or other application when the lock is not 10 required. This distinguishes padlocks from other forms of locks such as those that are mounted on or in doors, windows, gates etc. Padlocks also find use in a wide range of other applications. Typical padlocks are formed with a strong padlock body (generally of brass or steel), 15 and the padlock body usually contains a main opening. A cylinder (usually a key operated cylinder assembly) can be fitted in the main opening so that the padlock can be opened (usually by inserting and turning a key). Padlocks also typically have a shackle. The shackle generally comprises a rigid U 20 shaped metal member which can be formed from steel or brass. The parallel portions of the U-shaped shackle form two spaced apart parallel legs and one leg is generally longer than the other. In conventional padlocks, the longer leg passes through an opening in the top of the padlock body and is secured therein in such a manner that the leg cannot be pulled out. When the padlock is open, the secured long leg is often 25 able to pivot relative to the body about its axis so that the short leg moves in an arc around the long leg. The shackle is generally able to slide inwards and outwards within the opening in the body (although in conventional padlocks the shackle often cannot slide all the way out of the body because the long leg is retained as described above). 30 Typically, padlocks are locked by moving the shackle downwardly relative to the body so that the short leg inserts into a blind bore in the top of the padlock body. The short leg is then lockable therein to lock the padlock. With both legs of the shackle thus inserted, the shackle and body form a locked closed loop around the article or 2 thing secured by the padlock. The padlock can be unlocked by operating the cylinder, and a spring is typically provided to bias the shackle to the open condition (i.e. the shackle is biased to slide outwardly relative to the body under the bias when released so the short leg becomes retracted out of the body and can rotate about the long leg as 5 described above). Hence, where the cylinder is a key operated assembly, a key can be inserted into the barrel (i.e. the part of the assembly that receives the key) and turned to thereby release the shackle allowing the shackle to move upwardly into the open condition under the bias of the spring. 10 One disadvantage with many existing padlocks is that the shackle (and in particular the long leg thereof) is always attached to the padlock body and cannot be removed therefrom. It is often advantageous to have different types of shackles. For instance, for high security padlocks it is desirable to have a shackle made from a strong steel, while for normal padlocks the shackle can be made of a softer and possibly less 15 expensive metal or other material. With a nonremovable shackle, it is necessary to have a large number of padlocks each with a different shackle to satisfy these different requirements. The size and shape of the shackle can also vary for padlocks used in different applications, and sometimes it is necessary to have a shackle with a shape other than the typical U-shape. Again, if the shackle is always fixed to the 20 padlock body, it is necessary to have a large number of padlocks each with differently shaped shackles to satisfy these requirements. Another disadvantage associated with the inability to remove the shackle from the padlock body is that, in some cases the only way in which the padlock can be used is 25 by initially removing the shackle from the padlock body and placing it around the item to be locked before (re-)inserting the shackle back into the body to lock the padlock. This cannot be done if the shackle is permanently secured to the padlock body. 30 It would be desirable if locksmiths could stock a relatively small range of padlock bodies, and a large range of shackles compatible with the padlock bodies. A customer could then decide what type of padlock is required, and an appropriate combination of the correct shackle and padlock body could then be assembled accordingly. Also, if the customer desires the padlock to be used in a different application requiring an 3 alternative shackle, the alternative shackle may be purchased to allow the padlock to be applied to that new application without the need to buy an entirely new padlock. Hence, it may be advantageous to provide a padlock where the shackle can be 5 removed and replaced if desired when the padlock is open. It may also be advantageous if the shackle is not automatically or always removable when the padlock is open. Hence, it may be advantageous for the shackle to remain secured to the body when the padlock is open, unless the padlock is purposely operated while open to allow the shackle to be removed. One reason why it may be desirable for 10 padlocks to retain the shackle when open unless purposely operated to allow the shackle to be removed is because in some applications it is not necessary for the shackle to be removed in order to apply the padlock, and in such applications, if the shackle were to be removable always this might add an unnecessary complication to the operation of the padlock and there may be a risk that the shackle could be 15 misplaced. Preferably the mechanism by which the padlock can be purposely operated while open to allow removal of the shackle should be simple and easy to manufacture without requiring high precision in manufacturing tolerances. Another consideration is that whatever mechanism is used to enable the shackle to be 20 released from the padlock body, this mechanism should be relatively tamperproof such that the shackle cannot be removed in an unauthorised manner when the padlock is locked. Another problem that is commonly associated with traditional padlocks having a key 25 operated cylinder is that the key can be removed from the padlock at any time (i.e. irrespective of whether the padlock is open or locked). This means that it is possible for a user to remove the key from the padlock when the padlock is open, and the user may then leave without remembering to relock the padlock. Thus, there would be an advantage if it were possible to provide a padlock having a mode where the key is 30 retained in the padlock when the padlock is open so that the user cannot leave without relocking the padlock (at least not without leaving the key behind). It may also be advantageous for the padlock to be selectively convertible between this key holding mode and a removable key mode where the key can be removed from the padlock at any time. Possible reasons why it may be desirable to also have this removable key 4 mode is because in some applications it may be frustrating to have to lock the padlock before removing the key, or alternatively it may be necessary to use the key for another purpose while the padlock is open. Therefore, it may be desirable to provide a means for converting the padlock between the key holding mode and the removable 5 key mode. It will be clearly understood that any reference herein to background material, information or technical problems, or to a prior publication, does not constitute an admission that any material, information, publication or problems, or any combination 10 thereof, ever formed part of the common general knowledge in the art, or is otherwise admissible prior art, whether in Australia or in any other country. DESCRIPTION OF THE INVENTION It is an object of the invention to provide a padlock that at least partially ameliorates 15 one or more of the above-mentioned disadvantages, or which provides a useful or commercial alternative to existing padlocks. In a broad form, the present invention resides in a padlock having - a body 20 - a shackle at least part of which can be inserted relative to the body to lock the padlock and withdrawn relative to the body when the padlock is unlocked, - a cylinder for unlocking the padlock, - a locking element that can adopt a locking position in which the locking element engages the shackle when the shackle or part thereof is inserted to 25 prevent withdrawal of the shackle or part thereof, an unlocking position in which the locking element does not prevent the shackle or part thereof from being withdrawn but it prevents the shackle form being completely separated from the body, and a releasing position in which the locking element does not prevent the shackle from being completely separated from the body, 30 - locking means adapted to move the locking element into the locking position when the shackle or part thereof is inserted and which can be moved by operating the cylinder to allow the locking element to adopt the unlocking or releasing position, and 5 - a selector which can be operated from externally of the body to adopt a first position wherein the selector allows the locking element to adopt the locking and unlocking positions but prevents the locking element from adopting the releasing position, and a second position in which the selector allows the 5 locking element to adopt the releasing position. In another form, the invention resides in a padlock having - a body - a shackle at least part of which can be inserted relative to the body to lock the 10 padlock and withdrawn relative to the body when the padlock is unlocked, - a cylinder for unlocking the padlock, - a locking element that can adopt a locking position in which the locking element engages the shackle when the shackle or part thereof is inserted to prevent withdrawal of the shackle or part thereof, an unlocking position in 15 which the locking element does not prevent the shackle or part thereof from being withdrawn but it prevents the shackle form being completely separated from the body, and a releasing position in which the locking element does not prevent the shackle from being completely separated from the body, - locking means adapted to move the locking element into the locking position 20 when the shackle or part thereof is inserted and which can be moved by operating the cylinder to allow the locking element to adopt the unlocking or releasing position, and - a selector which can be operated from externally of the body, separately from the cylinder, when the shackle or part thereof is withdrawn to adopt a first 25 position wherein the selector allows the locking element to adopt the locking and unlocking positions but prevents the locking element from adopting the releasing position, and a second position in which the selector allows the locking element to adopt the releasing position. 30 Thus, the padlock shackle is retained by the body even when the padlock is open unless the selector is purposely operated to make the shackle removable from the body while the padlock is open. Preferably, it may only be possible to operate the selector to allow removal of the shackle while the padlock is open. The padlock may also be convertible between a removable key mode and the key holding mode.

6 The shackle of the present invention may be of any kind, shape or construction suitable to satisfy the requirements of the application in which the padlock is to be used. Consequently, the shackle may take a generally similar form to the traditional 5 rigid U-shaped shackles described in the background section above, or alternatively the shackle may be of some other nonconventional rigid shape suitable to adapt the padlock for use for a particular purpose. Furthermore, the shackle may take a non rigid form, for example a cable or chain of the kind often used to lock bicycles. It will therefore be understood that the present invention may be used with shackles having a 10 wide range of shapes, forms or constructions, and no limitation is intended in relation to the kind of shackle that may be used except as expressly stated herein. So that the padlock of the present invention may provide a suitable level of security, the shackle will preferably be constructed such that the shackle cannot easily be 15 broken, severed, separated or otherwise damaged or interrogated. Therefore, the shackle will preferably be formed from materials such as steel and the like, and in the event that the shackle takes a non-rigid form (for example a chain or wire etc), the shackle will be constructed in a manner known by the person skilled the art to be suitable for this purpose. 20 The shackle of the present invention will generally have leg members, and at least a portion of some or all leg members is insertable into the body of the padlock. For convenience, the padlock of the present invention will be described with reference to a shackle having two leg members and a body adapted to accommodate such a 25 shackle. However, the invention might also operate with a shackle having a greater number of leg members and a body adapted to receive some or all of those leg members. The two-leg shackle may take a form similar to the traditional rigid U-shaped shackle 30 and the two parallel portions of the "U" may form the leg members. Rigid shackles having other shapes adapted for use in specific applications may also be provided with two parallel portions which may form the leg members of the shackle. Alternatively, if the shackle takes the form of a non-rigid shackle such as a chain or wire, the opposed ends of the chain may be adapted to be insertable into the padlock body such 7 that the two ends of the chain form the two leg members of the shackle. To avoid confusion, if the shackle takes the form of a non-rigid shackle, the leg members thereof and the openings in the body for accommodating the leg members need not be parallel. 5 The leg members of the shackle may be of any shape, although in preferred embodiments one of the leg members may be substantially longer than the other of the leg members. It is also envisaged that in most embodiments, at least the portions of the leg members that are insertable into the padlock may be substantially straight. 10 Furthermore, whilst the leg members may have any cross-sectional shape, it is envisaged that at least the portions of the leg members that are insertable into the padlock may have a substantially circular cross-section. The body of the padlock may be of any size and shape, although it is envisaged that 15 the body may generally be substantially block shaped and sized to be easily operable by hand. The body may be made from any suitably robust material, but preferably robust metals such as steel or brass. However, it will be clearly understood that no particular limitation is intended in relation to the size or shape of the padlock body, or the material from which it may be made. 20 The body of the padlock may have an aperture to accommodate each leg member of the shackle. This may be a single aperture, but preferably there may be a plurality of separate apertures, one for accommodating each respective leg member of the shackle. If the body is substantially block shaped as envisaged, the body may therefore have an 25 upper surface defining a top wall of the body, and the top wall may contain the said apertures. The separate apertures may be in the form of bores extending downwardly into the body of the padlock, and it is envisaged that each bore may have a cross sectional shape corresponding to the cross-sectional shape of the leg member which it is adapted to accommodate. 30 If there are separate openings in the body of the padlock to accommodate the leg members, each of these openings may have a cross-sectional shape that corresponds with the cross-sectional shape of the leg member that it is adapted to accommodate. This is so that the leg members may insert snugly into the openings without leaving 8 any gaps that might allow for unauthorised tampering with the internal locking mechanism of the padlock. Consequently, if at least the portions of the leg members each have a substantially circular cross-section, then each of the openings in the body may have a corresponding substantially circular cross-section. Similarly for other 5 alternative cross-sectional shapes. For convenience, the invention will hereinafter be described with reference to embodiments wherein the insertable portions of the two leg members have a circular cross-section. The diameter of the insertable portion of one leg member may be the same as, or 10 different to that of the other leg member. Accordingly, the openings in the body that accommodate the leg members may have the same, or different diameters. The insertable portion of at least one leg member may have means for engaging with the locking element. This may preferably be the longer of the two leg members. The 15 means may comprise an aperture in the leg adapted to receive the locking element (hereinafter be referred to as a locking aperture). Preferably, the locking aperture may be in the form of a notch (a locking notch) extending in a direction substantially transverse to the longitudinal axis of the leg member, the notch being sufficiently large and deep so that when the locking element moves into the locking position it 20 may engage the notch to thereby prevent the leg member from moving axially within the aperture in the body. When the locking element moves into the locking position it may engage the notch by inserting into the notch. Even more preferably, the notch may have a substantially semi-tubular shape wherein the longitudinal axis of the notch is oriented substantially transversely to the longitudinal axis of the leg member, and 25 offset therefrom. This semi-tubular shape is particularly suitable when the locking element to comprises a ball. However, the invention is not necessarily limited to the locking element being a ball and the locking element could possibly take a wide range of other forms, for example a sliding member, rotating component etc. Nevertheless, for convenience the invention will be described with reference to embodiments where 30 the locking element is a ball (typically a metal ball). In fact, the invention will be described with reference to preferred embodiments having a pair of locking elements, each comprising a ball. In these embodiments, the leg members may be parallel, and each leg member may have a locking aperture (i.e. a locking notch) so that the apertures (notches) open substantially inwardly towards each other. However, the 9 locking apertures in the respective legs may alternatively take other forms and they may be positioned elsewhere on the leg members, so no particular limitation is meant in relation to the shape, form or location of the locking apertures. 5 The one leg member that is longer than the other leg member may have a further aperture therein (hereinafter referred to as a retaining aperture). The retaining aperture may be located below the locking aperture of the long leg member on the inner side. More particularly, the retaining aperture may be in the form of a flat recess extending downwardly from a lower edge of the locking aperture. The 10 retaining aperture may be indented into the leg member substantially less deeply than the locking aperture. The long leg member may also have a substantially circumferential groove therein. The groove may be recessed into the leg member approximately the same amount as the retaining aperture, and the groove may be positioned on the leg member such that the retaining aperture connects with the 15 groove. Hence, the retaining aperture and the groove may blend smoothly together. The functions of the groove and the retaining aperture will be explained in greater detail below. The long leg member may also have a bottom portion extending from the lower edge of the groove to the bottom end of the long leg member. The bottom portion may have substantially the same cylindrical diameter as the other portions of 20 the long leg member. The padlock further comprises locking means for moving the locking element into the locking position where it engages the shackle to prevent withdrawal of the shackle or part thereof. Preferably, the locking means may move the locking element (ball) into 25 engagement with the locking aperture (notch) in a leg member. Even more preferably, the locking means may move both of the locking elements (balls) into engagement with the apertures (notches) in the respective legs. Preferably, the locking means may comprise a camming member, although the locking means could alternatively take a range of other forms. The balls may be opposedly positioned on 30 respective sides of the camming member and the camming member may have an opposed pair of camming surfaces each of which may engage with a respective ball. The camming surfaces may be suitably curved to provide camming engagement with the balls.

10 The camming member may be rotatable between a closing position and an opening position. Rotation of the camming member into the closing position may cause each of the camming surfaces to engage the corresponding ball thereby pushing the balls outwardly into the locking position. If the leg members are inserted into the body, the 5 outward movement of the balls may cause the balls to engage with the locking apertures in the leg members. The engagement of the balls with the locking apertures may prevent the leg members from being retracted out of the body, thus locking the padlock. The camming member may be biased towards the closing position so that upon insertion of the leg members, the padlock automatically locks. 10 The camming member may also have an opposed pair of cavities adapted to receive the balls. The cavities may be interposed between the camming surfaces. Therefore, rotation of the camming member into the opening position may allow the balls to retreat inwardly at least some way into the cavities and out of engagement with the 15 locking apertures in the leg members. Where the or each ball (locking element) retreats inwardly at least some way into a cavity and out of engagement with the locking aperture, this is the unlocking position of a locking element in these embodiments. Upon disengagement of the balls with respect to the locking apertures, the leg members may be thereby released enabling each leg member (and therefore 20 the shackle) to move upwardly with respect to the body. More specifically, the leg members may be released by the retraction of the balls into the cavities because this may allow the lower edge of each of the locking apertures to move upwardly past the balls. This upward movement of the shackle may allow the short leg member to retract out of the body thus opening the padlock. 25 As described above, when the camming member is rotated into the opening position causing the balls to retreat into the cavities, this may allow the lower edges of the respective locking apertures to move upwardly past the balls. In the case of the short leg, this may allow the short leg member to be retracted out of the body of the 30 padlock. However, it will be recalled that the long leg member may have a retaining aperture extending downwardly from the lower edge of the locking aperture, and it may also have a groove positioned substantially near the bottom of the retaining aperture which extends circumferentially around the long leg member. The retaining aperture and the groove may be substantially less deep than the locking aperture in the l1 long leg member. Therefore, even though retraction of the ball at least some way into the cavity in the camming member (i.e. into the unlocking position) may disengage the ball from the locking aperture in the long leg member, nevertheless the ball may still extend outwardly sufficiently to engage with the retaining aperture and the 5 groove. This engagement of the ball with the retaining aperture and the groove, and in particular the engagement of the ball with a bottom edge of the groove which may form a lip, may prevent the long leg member from being retracted out of the padlock body, although the circumferential shape of the groove may allow the long leg member to rotate in the body. The engagement between the ball, the retaining 10 aperture and the groove may also prevent the camming member from rotating back into the closing position. This is because the retaining aperture and the groove may push the ball into, or hold the ball in, the cavity in the camming member. Therefore the camming member may only be able to rotate back into the locked position when the leg members are reinserted into the padlock to lock the padlock (or when both legs 15 are retracted from the padlock as described further below). Reinsertion of the leg members into the body may bring the locking apertures in the leg members back into alignment with the balls, thereby allowing the balls to move outwardly into the locking apertures thus allowing the camming member to rotate back into the locked position. 20 The padlock of the present invention has a selector which can be operated from externally of the body to adopt a first position wherein the selector allows the locking element (ball) to adopt the locking and unlocking positions but prevents the locking element (ball) from adopting the releasing position, and a second position in which 25 the selector allows the locking element to adopt the releasing position. Preferably, the selector may be movable into the second position to allow removal of the shackle only when the shackle is withdrawn relative to the body to open the padlock. This may prevent the selector from being moved into the second position in an un-authorised manner, because it means that the selector can only be moved into the second position 30 by someone having the correct key to first operate the cylinder (or the correct code to open the padlock etc - see below). The cavity in the camming member which receives the ball that engages with the long leg may be sufficiently large or deep to allow the ball to retreat into the cavity far 12 enough for the lip formed by the bottom edge of the groove in the long leg to pass by the ball, thereby allowing the shackle to be withdrawn and entirely separated from the body, when the selector is in the second position. When the ball (locking element) retreats far enough into the cavity to allow the lip of the long leg's groove to pass by, 5 this is the releasing position of the locking element in these embodiments. In preferred embodiments, the selector may comprise a selector screw. However, the selector could alternatively take a wide range of other forms, some of which are described further below. Where the selector comprises a selector screw, the screw 10 may be configured to block the ball that engages with the long leg from retreating all the way into the cavity in the camming member (i.e. to stop the ball from moving into its releasing position) when the selector screw is in the first position. However, when in the first position, the selector screw may still allow the ball to move between the locking position (where the ball engages with the locking aperture in the long leg to 15 lock the padlock) and the unlocking position (where the ball retracts enough to disengage from the locking aperture but remains engaged with the retaining aperture and the groove to retain the shackle to the body when the padlock is open). In the second position, the selector screw may not impede the motion of the ball at all. Therefore, when in the second position, the selector screw may allow the ball to move 20 between the locking position, the unlocking position and the releasing position. Preferably, the selector screw may be mounted in the padlock body so that the screw extends across the space through which the locking element (ball) moves when the locking element moves between the unlocking position and the releasing position. 25 The selector screw may have a cutout extending in a direction substantially transverse to the longitudinal axis of the screw. Suitably, the axis of the cutout may be oriented substantially transversely to the longitudinal axis of the screw, and the axis of the cutout may be offset from the longitudinal axis of the screw. The screw may be rotatable about its longitudinal axis relative to the body to change the direction that 30 the cutout is facing. In the first position, the cutout may face away from the locking element. In this orientation, the body of the screw (i.e. part of the screw which does not have a cutout in it) may occupy some of the space through which the locking element needs to pass to move from the unlocking position to the releasing position. Consequently, in the first position, the presence of the body of the screw in the said 13 space impedes the locking element and prevents the locking element from moving from the unlocking position to the releasing position. However, when the selector screw is rotated into the second position, the cutout may open into the space previously occupied by the body of the screw. Hence, when the selector screw is in 5 the second position, the locking element may be able to move from the unlocking position to the releasing position because the cutout may provide additional space (the space previously blocked off by the body of the screw) through which the locking element can pass to move into the releasing position. 10 The selector screw may be mounted near the camming member, and may interact with the camming member. Preferably, the way the selector screw interacts with the camming member may prevent the selector screw from being rotated from the first position into the second position except when the padlock is open. As explained above, when the camming member is in the closing position (generally meaning the 15 padlock is locked), a camming surface thereof is rotated to engage the locking element (ball) and push the locking element into engagement with the locking aperture in the shackle. Suitably, when the camming member is in the closing position, the selector screw may be oriented with the cutout facing towards the camming surface of the camming member. Preferably, in this configuration, part of 20 the camming member may extend at least partially into the cutout in the selector screw. In this configuration, the selector screw may be prevented from rotating from the first position to the second position because any attempt to rotate the selector screw while the camming member is in the closing position may cause an edge of the cutout in the selector screw to collide with the portion of the camming member 25 received in the cutout, preventing rotation of the selector screw. Therefore, in order to rotate the selector screw from the first position to the second position, it may be necessary to first rotate the camming member from the closing position to the opening position (using the cylinder). When the camming member is rotated into the opening position, the cavity in the camming member (i.e. the cavity into which the locking 30 element retracts when moving from the locking position to the unlocking position), or an extension of that cavity, may become aligned with the cutout in the selector screw. Therefore, when the camming member is in the opening position (which generally opens the padlock), rotation of the selector screw may not be impeded because the 14 additional space provided by the cavity may allow the edge of the cutout in the selector screw to pass by the camming member as the selector screw rotates. The screw should be operable from externally of the padlock. Preferably, the screw 5 may be accessible through an opening in the side of the padlock body, and the screw may be provided with engagement means to enable the screw to be manipulated from externally of the padlock. Suitably, the engagement means may enable the screw to be manipulated using a tool. The engagement means may comprise a hexagonal slot adapted to receive a hex wrench, or a slot adapted to receive a conventional 10 screwdriver, already similar arrangement. The selector screw may be provided with means to prevent the screw from being removed from the padlock body. As indicated above, the selector could take a range of forms other than a selector screw. For example, in one possible alternative form, the selector may comprise an 15 insertable and removable member such as a pin, spring pin or threaded bolt etc. In these alternative forms, the member that comprises the selector could be insertable in the padlock body so that the member extends across the space through which the locking element (ball) moves when the locking element moves between the unlocking position and the releasing position. Therefore, when inserted, the member may 20 prevent the locking element from moving into the releasing position, thereby preventing removal of the shackle. The member could be partially or entirely removable from the padlock body (although preferably only when the padlock is open) to enable removal of the shackle. More specifically, partial or full removal of the member may enable the locking element to move from the unlocking position to 25 the releasing position because the removal of the member may provide additional space (the space previously occupied by the member) through which the locking element can pass to move into the releasing position. In another possible alternative form, the selector may comprise a stepped pin (i.e. a 30 pin having a smaller diameter at one end and a larger diameter at the other end, the large and small diameters being separated by a step part-way along the pin). The stepped pin maybe inserted in a stepped bore in the padlock body. Preferably, a larger diameter portion of the stepped bore in the padlock body may extend across the space through which the locking element (ball) moves when the locking element moves 15 between the unlocking position and the releasing position. The stepped pin may be inserted into the bore so that the narrow end of the pin inserts snugly into the narrower end of the bore and the wide end of the pin fits snugly into the wider portion of the bore. The pin may be slidable back and forth within the bore. However, the extent of 5 the pin's movement in the direction of the narrow end of the pin may be restricted by the step in the pin coming into contact with the step in the bore. In this position (the first position) where the step in the pin contacts with the step in the bore, the wider portion of the pin may occupy at least part of the space through which the locking element (ball) needs to move in order to move between the unlocking position and the 10 releasing position. Hence, in this position, the stepped pin may prevent the locking element from adopting the releasing position, thereby stopping the shackle from being removed. After the stepped pin has been inserted into the padlock body through a hole in the 15 side of the padlock body which communicates with the wide portion of the stepped bore, a plug may be inserted to close the hole. A spring (such as a helical spring) may be inserted into the bore behind the pin before the plug is inserted so that, when the plug is inserted after the pin and spring, the spring is compressed between the plug and pin so as to push the pin in the direction of the narrow end of the pin. In other 20 words, the spring may push the pin into the bore forcing the step in the pin into contact with the step in the bore. The side of the padlock body opposite the plug may have an opening communicating with the narrow end of the stepped bore (hence allowing access to the narrow end of 25 the pin situated therein). An implement may be insertable through the opening to push on the pin moving it back against the bias of the spring, although this will preferably only be possible when the padlock is open. Moving the pin in this way may cause the step in the pin to move out of engagement with the step in the bore. Consequently, a narrow portion of the pin may then extend across part of the wide 30 portion of the bore leaving a gap between the narrow portion of the pin and the walls of the wide portion of the bore. This gap may provide additional space (space previously blocked off by the wider portion of the pin) through which the locking element can pass to move into the releasing position, thereby allowing the shackle to be removed.

16 In order to prevent unauthorised opening of the padlock, the cylinder used for operating the padlock may preferably comprise a key operated cylinder such that the cylinder is operable only upon insertion and rotation of the correct key in the barrel of 5 the cylinder. However, it will be clearly understood that the cylinder is not limited to keyed cylinders, and the cylinder may alternatively comprise any means or mechanism for operating the internal locking components of the padlock. For example, the cylinder could comprise an electric motor operable from externally of the padlock by remote control or by entry of a code into a keypad on the padlock 10 body. Hence, the term "cylinder" as used herein is not intended to limit in any way the shape or form of the component or group of components used to unlock the padlock. The cylinder of the padlock in most embodiments will comprise a key operated 15 cylinder. In relation to keyed cylinders, it will be understood that a key may only be inserted into the barrel of the cylinder, and it may only be retracted therefrom, when the barrel is in an aligned position. In other words, if a key is inserted into the barrel and rotated (for example to unlocked the padlock), the key cannot be removed from the barrel without rotating the key back in the opposite direction to thereby return the 20 barrel to the position that it was in when the key was inserted (this position will hereinafter be referred to as the aligned position). The importance of this will be explained in greater detail below. The body of the padlock may have a main opening to accommodate the cylinder. If 25 the body of the padlock is substantially block shaped as envisaged, then the body may have a lower surface defining a base of the body and the opening for accommodating the cylinder may be contained within the base, preferably extending up into the body through the base. Because the cylinder may be of any shape, the opening in the body of the padlock for accommodating the cylinder may also be of any shape. However, it 30 may be preferable for the opening in the body to be of a corresponding shape to that of the cylinder so that the cylinder fits snugly within the opening and no gaps or openings are left that may expose the inner workings of the padlock to unauthorised tampering.

17 The padlock may comprise an entraining member operatively associated with the cylinder so that operation of the cylinder imparts corresponding rotation to the entraining member. The entraining member may comprise a part or extension of the cylinder, or a separate component attachable to the cylinder, although no particular 5 limitation is meant thereby. Preferably, the entraining member may be adapted to operatively connect the cylinder with the locking means so that rotation of the cylinder or a component of the cylinder (typically the cylinder barrel) from the aligned position to an unaligned position causes disengagement of the locking elements from the locking aperture in the leg members. Even more preferably, the 10 locking means may comprise a camming member as described above and the entraining member may be adapted to cooperate with the camming member so that rotation of the cylinder or component thereof (and hence the entraining member) thereby causes rotation of the camming member from the closing position to the opening position. 15 To achieve this the entraining member may be provided with one or more protrusions that cooperate with one or more corresponding protrusions on the camming member. In particularly preferred embodiments, the one or more protrusions on the entraining member may comprise a pair of upwardly extending entraining posts. The protrusions 20 on the camming member may take any form suitable to cooperate with the entraining posts, but for convenience the protrusions on the camming member will be referred to as the cam blocks. The entraining posts may be positioned such that, when the padlock is assembled, one 25 of the entraining posts is located on one side of the cam blocks, and the other entraining post is located on the other side of the cam blocks. In this way, rotation of the entraining member (caused by operation of the cylinder) in one direction causes the entraining posts to come into contact with the cam blocks, whilst rotation of the entraining member in the other direction causes the entraining posts to separate from 30 the cam blocks. Hence, the entraining member may be able to rotate somewhat independently of the camming member. A key retainer element may be provided to restrict this free movement as described further below.

18 As explained above, the camming member may only be able to rotate from the opening position back into the closing position when the leg members are reinserted into the padlock to lock the padlock (or when both legs are retracted from the padlock). Therefore, when the padlock is opened by operating the cylinder which in 5 turn rotates the entraining member and the camming member, the camming member may then be retained in the opening position until the leg members are reinserted. Meanwhile (i.e. while the camming member is retained in the opening position), the entraining member and the cylinder mechanism may be able to rotate back in the other direction freely (at least within a certain range of motion). If the entraining 10 member and the cylinder mechanism are able to rotate freely in this way, it may therefore be possible to return the cylinder or component thereof (typically the barrel) to the aligned position. Thus, if the entraining member and the cylinder mechanism are able to rotate freely, and if the cylinder comprises a keyed cylinder, then this may allow the key to be extracted from the key barrel while the padlock is open, thus 15 placing the padlock in the removable key mode. The key retainer element mentioned briefly above may be used to convert the padlock from the removable key mode to the key holding mode. It may do this by fixing the entraining posts into engagement with the cam block. By doing this, the key retainer 20 element would prevent the entraining member and the cylinder from rotating freely with respect to the camming member, and if the cylinder is a key operated cylinder, this would thereby prevent the key from being rotated back into the aligned position when the padlock is open. In preferred embodiments, the key retainer member may comprise a pin that is selectively insertable and removable from an aperture in the 25 entraining member. However, the key retainer element may comprise any other means for maintaining the entraining posts in engagement with the cam block, and no particular limitation is meant in relation to the kind of key retainer element that may be used. 30 In some particularly preferred embodiments, the key retainer pin may be insertable into the said aperture in the entraining member to convert the padlock into the key holding mode, but one of the entraining posts may also have an aperture for receiving the pin. In these embodiments, when the pin is inserted into the aperture in the entraining post, the pin may be wholly contained therein merely for the purposes of 19 storage and the entraining member may then operate otherwise as if the pin were not present. Thus, in these embodiments insertion of the pin into the pin receiving aperture in the entraining member may convert the padlock into the key holding mode, whilst insertion of the pin into the aperture in the entraining post may convert 5 the padlock into the removable key mode. It will be clearly understood that the body of the padlock may comprise whatever forms of internal shaping, sculpting or other features that may be necessary to house, mount, interrelate and interoperate with the various components of the padlock. 10 BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention are described below with reference to the drawings. However, it will be clearly appreciated that these embodiments are described for the purposes of illustration only and the invention is not necessarily limited to or by the 15 particular features described. In the drawings: Figure I is an exploded perspective representation of a padlock in which some of the features of the present invention are missing but which is nevertheless shown for the purposes of describing certain other features which may form part of, or be 20 used with, padlocks in accordance with the present invention, Figure 2 is a partially exploded perspective representation of a padlock in accordance with one embodiment of the invention, Figure 3 is a partially exploded perspective view similar to Figure 2, except in "wireframe", 25 Figure 4 is a partially cross-sectional front view of the padlock of Figure 2 when the padlock is locked, Figure 5 is a cross-sectional view of the padlock taken along the line B-B in Figure 4, Figure 6 is a partial cross-sectional front view of the padlock of Figure 2 when 30 the padlock is open, Figure 7 is a partial cross-sectional front view of the padlock of Figure 2 when the padlock is open and the selector is in the second position to allow the shackle to be removed, 20 Figure 8 is a partial cross-sectional front view of the padlock of Figure 2 when the padlock is locked, Figure 9 is a partial perspective view of the padlock of Figure 2 when the padlock is locked, 5 Figure 10 is a partial perspective view of the padlock of Figure 2 (from a different perspective to Figure 9) when the padlock is locked, Figure I1 is a partial cross-sectional front view of the padlock of Figure 2 when the padlock is in the shackle retaining mode and open, Figure 12 is a partial perspective view of the padlock of Figure 2 when the 10 padlock is open, Figure 13 is a partial cross-sectional front view of the padlock of Figure 2 when the padlock is open and the selector is in the second position to allow the shackle to be removed, Figure 14 is a partial perspective view of the padlock of Figure 2 when the 15 padlock is open and the selector is in the second position to allow the shackle to be removed, Figure 15 is a partially cross-sectional front view of a padlock in accordance with another embodiment of the invention when the padlock is locked, Figure 16 is a side on view of the padlock of Figure 15 when the padlock is 20 locked, Figure 17 is a partial perspective view of the padlock of Figure 15 when the padlock is locked, Figure 18 is a partially cross-sectional front view of the padlock of Figure 15 when the padlock is open, 25 Figure 19 is a side on view of the padlock of Figure 15 when the padlock is open, Figure 20 is a partial perspective view of the padlock Figure 15 when the padlock is open, Figure 21 is a partially cross-sectional front view of the padlock of Figure 15 30 when the padlock is open and the selector is in the second position to allow the shackle to be removed, Figure 22 is a side on view at the padlock of Figure 15 when the padlock is open and the selector is in the second position allowing the shackle to be removed, and 21 Figure 23 is a partial perspective view of the padlock of Figure 15 when the padlock is open and the selector is in the second position to allow the shackle to be removed. 5 BEST MODE As explained above, Figure 1 shows a padlock in which some of the features of the present invention are missing but which is nevertheless shown for the purposes of describing certain other features which may form part of, or be used with, padlocks in accordance with the present invention. Figures 2-14 show a padlock in accordance 10 with one embodiment of the invention. Features of the padlock in Figure 1 which also form part of the embodiment of the invention in Figures 2-14 will be referred to using the same reference numerals in Figures 2-14 as in Figure 1. Figures 15-23 show a padlock in accordance with another embodiment of the invention, and again, like features in Figures 15-23 will be referred to using like reference numerals. 15 Figure 1 shows a padlock having a body 12 and a shackle 14. Shackle 14 comprises a long leg 16 and short leg 18, and body 12 comprises a long leg bore 20 and a short leg bore 22. Long leg 16 is adapted to be insertable into long leg bore 20, and short leg 18 is adapted to be insertable into short leg bore 22. 20 Referring now to shackle 14, it can be seen that, in the orientation in the Figures, the general shape of shackle 14 is similar to that of an inverted "U". Therefore, the two parallel portions of the U form long leg 16 and short leg 18, and the upper end of the respective legs are integrally connected by an arcuate member 24 corresponding to the 25 curved portion of the U. More specifically, in the embodiment shown, long leg 16 and short leg 18 are both substantially cylindrical (i.e. having a substantially circular cross-section) of equal diameter, and long leg 16 is substantially longer than short leg 18 so that the lower end of long leg 16 extends substantially below the lower end of short leg 18. Because the respective legs are substantially cylindrical, therefore 30 arcuate member 24 (which is integrally formed with the legs) has a substantially semi toroidal shape connecting the tops of the two legs and having approximately the same cross-section as the legs.

22 Both long leg 16 and short leg 18 have a locking notch 26, 28 therein. Notches 26, 28 comprise substantially semi-tubular or part-circular cutouts in the inner side of the respective legs, the cutouts being oriented such that the longitudinal axis of each semi-tubular cutout is substantially perpendicular to the longitudinal axis of the 5 respective legs and offset inwardly thereof. Notch 28 in short leg 18 is located towards the lower end of short leg 18, and notch 26 in long leg 16 is located approximately midway down the length of long leg 16 such that both the notches are located at substantially the same level, thus effectively making each notch a mirror image of the other. 10 Long leg 16 further comprises a groove 30, a retaining aperture in the form of inner flat 32, a bottom portion 34. Groove 30, located towards the lower end of long leg 16, has a substantially part-circular cross-section and extends all the way around long leg 16. Thus, groove 30 forms a substantially circumferential cutout around the lower end 15 of long leg 16. Importantly, the maximum depth to which groove 30 is recessed into long leg 16 is substantially less than the maximum depth to which notches 26, 28 are indented into the respective leg members. The reason for this will be explained below. 20 Inner flat 32 comprises a substantially flat surface extending down the inner side of long leg 16 from the lower edge of notch 26 to groove 30. Inner flat 32 is also slightly indented into long leg 16 and it therefore forms a slightly recessed flat surface. The depth to which inner flat 32 is recessed into long leg 16 is approximately the same as the depth of groove 30. Therefore, inner flat 32 effectively blends 25 smoothly into groove 30 at the point where the two intersect, and there is no distinct ridge, edge or other delineation between the two. Bottom portion 34 is the portion of long leg 16 extending downwardly below groove 30. The bottom portion 34 has the full diameter of long leg 16. Thus, the edge where 30 groove 30 meets bottom portion 34 forms a lip 37. Referring again to Figure 1, it can be seen that the padlock has an internal locking mechanism 38 for locking and unlocking the padlock. Locking mechanism 38 comprises key cylinder 40, cylinder retainer 41, entraining member 42, camming 23 member 44, a spring 45 (only shown in Figure 1) to bias camming member 44 to the closing position, plate 47 against which the spring pushes to bias camming member 44, and locking balls 46, 48. The key cylinder 40 incorporates a conventional key barrel 39 into which a key can be inserted and rotated (which causes the barrel to 5 rotate relative to the rest of the cylinder) in the usual way. The key barrel 39 is visible in Figure I because part of the cylinder 40 is shown "cutaway" to reveal the barrel. Together, key cylinder 40 and cylinder retainer 41 form a key mechanism which is shaped generally as a "figure 8"-like prism, and which is insertable into a 10 correspondingly "figure 8" shaped bore 50 in the bottom of body 12. Key mechanisms of this type are conventional and therefore require no further explanation. Hence, it will be understood that a key may be inserted into the barrel 39 of key cylinder 40 and that, if the key is the correct key for the barrel, the key will then be able to rotate the key barrel. It will also be understood that rotation of the key and key 15 barrel causes the end of the cylinder 40, or a portion thereof, or a pin or other abutment, to rotate accordingly. This causes rotation to be imparted into the other components of locking mechanism 38 to operate the padlock as explained in greater detail below. 20 It can be seen that camming member 44 comprises a pair of convex camming surfaces 56 located on opposite sides thereof, and a pair of concave cavities 58 also located on opposed sides thereof and interposed between the camming services 56. The locking balls 46, 48 are positioned one on either side of calming member 44. Camming member 44 is pivotable between a closing position and an opening position. Figure 1 25 shows camming member 44 in the closing position where (if it were assembled inside the padlock) the camming surfaces 56 contact with the balls 46, 48, thereby pushing ball 46 into engagement with notch 26 in long leg 16 and pushing ball 48 into engagement with notch 28 in short leg 18. It will be clearly understood that the diameter of each of the balls 46, 48 is such that balls 46, 48 fit snugly and sufficiently 30 deeply into notches 26 and 28 when the legs are inserted so as to prevent vertical movement of the respective legs within the body. Thus, when camming member 44 is in the locked position and both legs of the shackle are inserted into their respective bores in body 12, the legs are retained within body 12 by engagement of the balls 46, 48, and the padlock is locked.

24 Camming member 44 can be pivoted from the closing position into the opening position by rotating camming member 44 approximately 900 in the direction indicated by arrow "A" in Figure 1 (counter clockwise when viewed from above). This is done 5 by operating key cylinder 40, as explained in greater detail below. When camming member 44 is pivoted into the unlocked position, locking balls 46, 48 are no longer in engagement with camming surfaces 56 and therefore they are not being pushed into engagement with the notches 26 and 28 in the legs. Instead, 10 locking balls 46, 48 are allowed to retreat at least some way into the cavities 58 in camming member 44. It will be understood that this allows the bottom edges of the respective notches 26 and 28 to move upwardly past balls 46, 48. Hence, rotation of camming member 44 into the opening position allows legs 16 and 18 of the shackle to move upwardly within the body 12. In particular, it allows short leg 18 to be retracted 15 entirely out of short leg bore 22, thus opening the padlock. However, it will also be understood that, even when ball 46 is retracted some way into the corresponding recess 58 in the long leg, it is not retracted entirely within the recess. The reason ball 46 does not retreat all the way into the recess is explained in 20 more detail below. In any event, because ball 46 does not retreat all away into the recess, it extends outwardly to some extent even when it is retracted, albeit to a lesser extent than it does when it is pushed into engagement with notch 26 by camming surfaces 56. It will be recalled that inner flat 32 (which is recessed slightly into long leg 16 but less deeply than notch 26) extends down the inside of long leg 16 between 25 the lower edge of notch 26 and groove 30. Therefore, even though ball 46 retracts out of notch 26 when the balls are retracted into cavities 58, nevertheless ball 26 still extends outwardly sufficiently to engage with inner flat 32. It will also be recalled that the lower edge of groove 30 forms a lip 37. Therefore, even when ball 46 is retracted into cavities 58 and the short leg 18 is retracted out of short leg bore 22 so 30 that the padlock is open, nevertheless the engagement of ball 46 with inner flat 32 and lip 37 prevents long leg 16 from being retracted out of long leg bore 20. This is illustrated in Figure 6.

25 The cavity 58 in camming member 44 which receives ball 46 is sufficiently deep to allow ball 46 to retreat into the cavity far enough for the lip 37 to pass up past the ball, thereby allowing the shackle to be withdrawn and entirely separated from the body. However, this can only happen when the selector is in the second position - see 5 below. When the ball 46 retreats far enough into the cavity 58 to allow the lip 37 to pass by, this is the releasing position of the ball 46. The reason ball 46 does not retreat all away into the recess 58 (except as described below) is because it is prevented from doing so by selector screw 70. The selector 10 screw 70 is mounted in the body 12 so that the screw extends across the space through which ball 46 needs to move to retract all the way into recess 58. The way screw 70 extends through this space can be appreciated from Figure 3. The selector screw 70 has a cutout 71 extending in a direction transverse to the 15 longitudinal axis of the screw. The axis of cutout 71 is transverse to the longitudinal axis of the screw, and is offset from the longitudinal axis of the screw. The screw is rotatable about its longitudinal axis (as shown by arrow "D" in Figure 2) to change the direction that the cutout 71 is facing. In the position of the screw 70 shown in Figure 4, 8-12, the cutout 71 faces away from the ball 46. In this orientation, the body of the 20 screw (i.e. the part of the screw which does not have a cutout in it) occupies some of the space through which the ball 46 needs to pass to retreat all the way into the cavity 58. Consequently, when the screw 70 is in this position (the first position), even if the camming member is rotated to make the recess 58 point towards the ball 46 (as shown in Figure 11-12), the presence of the body of screw 70 in the space impedes the ball 25 46 and prevents the ball from retreating all the way into the cavity 58. However, when the screw 70 is rotated into the position shown in Figures 7, 1 3-14 (the second position), the cutout 71 opens into the space previously occupied by the body of the screw. Hence, when the screw 70 is in the second position, the ball 46 can retreat all the way into the cavity 58 because the cutout 71 provides additional space (the space 30 previously blocked off by the body of the screw) through which the ball can pass to retreat. The selector screw 70 is mounted near camming member 44, and interacts with the camming member. In fact, the way selector screw 70 interacts with camming member 26 44 prevents the selector screw from being rotated from the first position into the second position except when the padlock is open. As explained above, when camming member 44 is in the closing position (generally meaning the padlock is locked), a camming surface 56 thereof engages ball 46 and pushes it into engagement 5 with the locking notch 26 in the shackle. The camming member 44 in Figures 2-14 is slightly different to the camming member 44 in Figure 1. In particular, the camming member 44 and Figures 2-14 has a round squat protuberance 59 extending from the top. As shown quite clearly in Figures 2 and 3, the cavities 58 in the camming member 44 extend up into the protuberance 59 to form small cutout portions in the 10 protuberance. As shown in Figure 4, 8-10, when camming member 44 is in the closing position, selector screw 70 is oriented with the cutout 71 facing towards the protuberance 59. In fact, in this configuration, part of the round edge of protuberance 59 extends 15 partially into cutout 71. This is shown quite clearly in Figure 9. In this configuration, selector screw 70 is prevented from rotating because any attempt to do so would cause an edge 72 of cutout 71 to collide with the portion of protuberance 59 that is received in the cutout, thus preventing rotation of the selector screw 70. 20 In order to rotate the selector screw 70, it is necessary to first rotate the camming member 44 from the closing position to the opening position (using the cylinder). Views of the padlock with the camming member 44 rotated into the opening position are given in Figures I1 and 12. When the camming member 44 is rotated into the opening position as shown, the recess 58 in the camming member (and the extension 25 of the recess 58 which extends into the protuberance 59) becomes aligned with the cutout 71 in the selector screw. Therefore, when camming member 44 is in this position which opens the padlock, rotation of the selector screw 70 is not impeded because the additional space provided by the recess 58 (and the extension of it in the protuberance 59) allows the edge 72 of the cutout to pass by as the selector screw 30 rotates. Figures 7, 13 and 14 illustrate the way screw 70 can be rotated allowing ball 46 to retract all the way into the cavity 58 when camming member 44 is in the opening position. They also illustrate the way the shackle can then be removed completely from the body.

27 The screw 70 is accessible through an opening 80 in one side of the padlock body. The opening 80 is shown in Figures 10, 12 and 14. The screw 70 has a hexagonal slot in the end near opening 80 which can receive a hex wrench. Hence, a hex wrench can be inserted into the hexagonal slot through opening 80 to turn the selector screw 70 5 when the padlock is open as described above. When the padlock is initially assembled, the selector screw 70 is inserted into the padlock body through an opening 82 in the other side of the body. Opening 82 is shown clearly in Figure 2 and 3. Once the screw 70 has been inserted, a plug 84 is inserted into opening 82 to close opening 82. Plug 84 is securely retained in opening 82 by a tight interference fit. When the 10 surface of body 12 is buffed to give the body its final finish, any lines marking the delineation between the plug 84 and the rest of the body are removed, effectively hiding the plug. A similar method is used to hide the plug 86 which is inserted to close the hole in the side of the body through which other components are inserted. 15 Because the whole 82 through which the selector screw 70 is inserted is closed by plug 84, it is not possible to access the screw from that side of the body once the plug has been inserted. The end of the screw 70 nearest the plug 84 is slightly wider than the remainder of the screw. This prevents the screw being "pulled through" the padlock. This configuration effectively prevents removal of screw 70. 20 Referring again to the situation where the screw 70 is rotated to the position where it prevents removal of the shackle from the body, it will be appreciated that the circumferential shape of groove 30 allows long leg 16 to rotate within long leg bore 20 (i.e. shackle 14 can be rotated about long leg 16) when the padlock is open. 25 Groove 30 effectively creates a track within which ball 46 can roll as shackle 14 rotates. Figure 1 shows that entraining member 42 comprises a substantially disk shaped member having approximately the same diameter as key cylinder 40 (i.e. 30 approximately the same diameter as one lobe of the "figure 8"). It can also be seen from Figure 1 that entraining member 42 is secured to the top of the key cylinder 40, coaxially therewith, by a pair of screws 52. Hence, rotation of key barrel 39 by a key in the manner described above causes corresponding rotation of entraining member 42. The heads of screws 52 sit approximately flush with, or slightly below, the upper 28 surface of entraining member 42 when the screws are inserted. This prevents the screws from interfering with the operation of entraining member 42. Entraining member 42 also has a pair of entraining posts 54. The respective entraining posts 54 are positioned directly opposite each other on the upper surface of entraining member 5 42, towards the outer edge thereof, and they extend vertically upwards. Camming member 44 has a pair of cam blocks 60 protruding downwardly from its base. One of the cam blocks 60 can be seen in Figure 1. When the padlock is assembled, cam blocks 60 reside between the respective entraining posts 54 of 10 entraining member 42. Hence, rotation of entraining member 44 (caused by rotation of the key barrel 39) in the direction indicated by arrow "A" in Figure 1 causes entraining posts 54 to come into contact with cam blocks 60. Conversely, rotation of entraining member 42 in the opposite direction causes entraining posts 54 to separate from cam blocks 60. Hence, the entraining member 44 can rotate somewhat 15 independently of the camming member 44. A relocatable key retainer pin 62 is also shown, but this will be described in greater detail below. It will be appreciated from the above description, and from Figure 1, that camming member 44 can rotate from the opening position back into the closing position only 20 when the legs 16 and 18 are reinserted into bores 20 and 22 to lock the padlock (or when both legs are retracted from the bores). Therefore, when key barrel 39 is operated which in turn rotates entraining member 42 and camming member 44, camming member 44 becomes retained in the opening position until the legs 16, 18 are reinserted. Meanwhile (i.e. while camming member 44 retained in the opening 25 position), if pin 62 is not present, entraining member 42 is able to rotate freely. It is therefore possible to return the key barrel 39 to the aligned position and extract the key while the lock is open. Relocatable key retainer pin 62 mentioned briefly above is used to convert the 30 padlock from the removable key mode to the key holding mode. It does this by fixing entraining posts 54 into engagement with the cam blocks 60. By doing this, relocatable pin 62 prevents entraining member 42 and key barrel 39 from rotating freely with respect to the camming member 44, thereby preventing key barrel 39 from being rotated back into the aligned position when the padlock is open. This therefore 29 prevents the key from being retracted when the padlock is open. Relocatable pin 62 is selectively insertable and removable from an aperture in entraining member 42 as shown in Figure 1. It is also insertable into a further aperture (not shown) contained within one of the entraining posts 54 for storage. This latter aperture takes the form of 5 a bore of corresponding shape to relocatable pin 62 such that insertion of relocatable pin 62 into the further aperture allows entraining member 42 to operate as if relocatable pin 62 were not present. Thus, the padlock according to this embodiment of the present invention contains a 10 shackle that can be retained to the padlock body but which can also to be completely removed from the padlock body when the padlock is open using a simple tamper resistant mechanism. The padlock can also be converted from the removable key mode to the key holding mode. 15 Figures 15-23 illustrate a possible alternative embodiment of the invention where the selector comprises a stepped pin 90 instead of the selector screw 70 in Figures 2-14. Stepped pin 90 has a smaller diameter at one end 92 and a larger diameter at the other end 94. The large diameter 94 and small diameter 92 are separated by a step (i.e. a discontinuous change in the pin width) part-way along the pin. Pin 90 is inserted in a 20 stepped bore 100 in the padlock body (see Figures 22-23). The larger diameter portion 104 of bore 100 extends across the space through which the locking ball 46 moves when the it moves between the unlocking position and the releasing position. Stepped pin 90 is inserted into bore 100 so that the narrow end 92 of the pin inserts snugly into the narrower end 102 of the bore and the wide end 94 of the pin fits 25 snugly into the wider portion 104 of the bore. The pin is slidable back and forth within the bore. However, when the pin is inserted, the extent of the pin's movement in the direction of narrow end 92 is restricted by the step in the pin coming into contact with the step in the bore. In the position (the first position) where the step in the pin contacts with the step in the bore, the wider portion 94 of the pin occupies at least part 30 of the space through which the locking ball 46 needs to move in order to move between the unlocking position and the releasing position. Hence, in this position, the pin prevents the ball from adopting the releasing position, thereby stopping the shackle from being removed.

30 After the stepped pin has been inserted into the padlock body through a hole in the side of the padlock body which communicates with the wide portion 104 of the bore, a plug 110 is inserted to close the hole. The plug is held in place by a tight interference fit. A helical spring 112 is inserted into the bore behind the pin 90 before 5 the plug I10 is inserted so that, when the plug 110 is inserted after the pin and spring, the spring is compressed between the plug and pin so as to push the pin in the direction of the narrow end 92 of the pin. In other words, the spring pushes the pin into the bore 100 forcing the step in the pin into contact with the step in the bore. 10 The side of the padlock body opposite the plug has an opening 82 communicating with the narrow end 102 of the bore (hence allowing access to the narrow end 92 of the pin). An implement (such as a piece of wire or some other tool) can be inserted through opening 82 to push on the pin 90, thus moving the pin 90 back against the bias of the spring 112. Moving the pin in this way causes the step in the pin to move 15 out of engagement with the step in the bore. Consequently, part of the pin's narrow end 92 then extends across part of the wide portion 104 of the bore leaving a gap between the narrow portion 92 of the pin and the walls of the wide portion 104 of the bore (see Figure 22-23). This gap provides additional space (space previously blocked off by the wider portion 94 of the pin) through which the locking ball 46 can 20 pass to move into the releasing position, thereby allowing the shackle to be removed. It should be appreciated that various changes and modifications can be made to the embodiments described without departing from the spirit and scope of the invention.

Claims (23)

1. A padlock having a body a shackle at least part of which can be inserted relative to the body to lock the padlock and withdrawn relative to the body when the padlock is unlocked, a cylinder for unlocking the padlock, a locking element that can adopt a locking position in which the locking element engages the shackle when the shackle or part thereof is inserted to prevent withdrawal of the shackle or part thereof, an unlocking position in which the locking element does not prevent the shackle or part thereof from being withdrawn but it prevents the shackle form being completely separated from the body, and a releasing position in which the locking element does not prevent the shackle from being completely separated from the body, locking means adapted to move the locking element into the locking position when the shackle or part thereof is inserted and which can be moved by operating the cylinder to allow the locking element to adopt the unlocking or releasing position, and a selector which can be operated from externally of the body to adopt a first position wherein the selector allows the locking element to adopt the locking and unlocking positions but prevents the locking element from adopting the releasing position, and a second position in which the selector allows the locking element to adopt the releasing position.

2. A padlock as claimed in claim I wherein the selector can only be operated when the shackle or part thereof is withdrawn.

3. A padlock as claimed in any one of the preceding claims wherein the shackle is U-shaped and the two parallel portions of the "U" form leg members of the shackle, one leg member being longer than the other and the long leg member having a locking aperture in the form of a notch for receiving the locking element which comprises a ball.

4. A padlock as claimed in claim 3, wherein the shorter leg member also has a locking aperture for receiving a locking element, the padlock having two locking 32 elements each comprising a ball, and the locking aperture in each leg comprising a notch with which a respective ball can engage.

5. A padlock as claimed in claim 4 wherein the locking means comprises a camming member rotatable between a closing position and an opening position, the balls being positioned on respective sides of the camming member and the camming member having opposed camming surfaces which engage with the respective balls such that, if the leg members are inserted into the body, rotation of the calming member into the closing position causes the camming member to push the balls into engagement with the notches.

6. A padlock as claimed in claim 5, wherein the camming member has opposed cavities, between the camming surfaces, which are adapted to receive the balls such that rotation of the camming member into the opening position allows the balls to retreat inwardly at least some way into the cavities and out of engagement with the notches in the leg members.

7. A padlock as claimed in claim 6, wherein the long leg of the shackle has a retaining aperture and/or a groove which extends circumferentially around the long leg member, wherein when the camming member rotates into the opening position allowing the balls to retreat into the cavities, if the selector is in the first position, the ball which engages the notch in the long leg nevertheless still extends outwardly sufficiently to engage with the retaining aperture and/or groove thereby preventing the shackle from being completely separated from the body.

8. A padlock as claimed in claim 7, wherein the cavity in the camming member which receives the ball that engages with the long leg is sufficiently large that that ball is able to retreat into that cavity far enough for the retaining aperture and/or groove on the long leg member to pass by that ball, thereby allowing the shackle to be completely separated from the body, if the selector is in the second position.

9. A padlock as claimed in claim 8, wherein the selector comprises a rotatable selector element which can rotate between the first position and the second position. 33

10. A padlock as claimed in claim 9, wherein when the selector element is in the first position it blocks the ball that engages with the long leg from retreating all the way into the cavity in the camming member.

11. A padlock as claimed in claim 10, wherein the ball which engages with the long leg of the shackle moves within a space inside the body when it moves between the unlocking position and the releasing position, and the selector element is mounted in the body so that it can extend at least partially through that space.

12. A padlock as claimed in claim 11, wherein the selector element has a cutout extending in a direction substantially transverse to its longitudinal axis.

13. A padlock as claimed in claim 12, wherein the cutout faces away from the locking element when the selector element is in the first position such that at least some of the element occupies some of the space through which the locking element needs to pass to move from the unlocking position to the releasing position.

14. A padlock as claimed in claim 13 wherein the cutout opens into the said space when the selector element is in the second position, thus providing room for the locking element to move from the unlocking position to the releasing position.

15. A padlock as claimed in any one of claim 9-14, wherein the rotatable selector element comprises a selector screw.

16. A padlock as claimed in claim 15, wherein when the camming member is in the closing position, the selector screw is oriented with the cutout facing towards the camming member and the selector screw is prevented from rotating from the first position to the second position because any attempt to do so causes a portion of the cutout to collide with the camming member.

17. A padlock as claimed in claim 16, wherein when the camming members in the opening position, rotation of the selector screw is not impeded because the additional space provided by the cavity in the camming member allows the cutout in the selector screw to pass by the camming member. 34

18. A padlock as claimed in any one of claims 9-17, wherein the selector is accessible through an opening in the side of the padlock body.

19. A padlock as claimed in any one of claims 1-8, wherein the selector comprises an insertable and at least partially removable component.

20. A padlock as claimed in any one of claims 1-8, wherein the selector comprises a pin member having a wider portion and a narrower portion, wherein when the pin member is in the first position the wider portion occupies some of the space through which the locking element needs to pass to move from the unlocking position to the releasing position.

21. A padlock as claimed in claim 20, wherein the padlock body has an opening to enable an implement to be inserted to slide the pin member from the first position to the second position against the bias of a spring, wherein when the pin member is in the second position the narrow portion of the pin provides additional space through which the locking element can pass to move into the releasing position.

22. A padlock as claimed in any one of the preceding claims which is convertible between a key holding mode and a removable key mode.

23. A padlock substantially in accordance with any embodiment hereinbefore described with reference to the accompanying drawings.